This invention relates to welding apparatus for making metal honeycomb core panels.
Welding apparatus for making metal honeycomb typically utilize probe-like welding elements adapted to make one spot weld at a time between the outer nodes of a honeycomb core, as is generally illustrated and described in U.S. Pat. No. 2,927,991 to Schoelz. (The word "outer nodes" is used herein to describe those nodes adjacent the edge of a honeycomb core panel which are formed by engagement of the inwardly directed apices of a corrugated metal sheet with outwardly directed apices of a partly formed honeycomb core.) Inasmuch as a typical weld joint across each node is made up of many spot welds, the prior art welding process is time consuming, inefficient, and costly. Wheel type electrodes are not significantly faster than probe type electrodes. Both probe and wheel type electrodes require complicated positioning and control equipment which increases installation and operating costs of the apparatus.
Metal honeycomb welding apparatus also typically includes one or more generally parallel rows of substantially vertical finger electrodes which may be inserted through the honeycomb core spaces of the core panel to position it and successive strips as generally illustrated and described in U.S. Pat. No. 2,821,616 to Spott. The Spott finger electrodes lend structural simplicity and increased reliability to the apparatus because they perform multiple functions, one of which is to advance the assembled core out the rear of the apparatus as their relative forward and rear positions are being interchanged subsequent to welding a strip to the end of the core panel. One drawback to the Spott apparatus and other similar prior art welding devices is that the core panel is assembled from a planar strip formed into the desired corrugated shape using the finger electrodes as corrugated die sections. This is undesirable because the completed core panel is likely to have irregular cell configurations and/or have nonplanar faces due to strip misalignment caused by the shaping process.
It is an object of the present invention, therefore, to overcome or mitigate the disadvantages of these and other prior art welding apparatus for making metal honeycomb from previously formed corrugated metal strips by providing a method and apparatus for producing substantially simultaneously multiple spot welds across one, two or more nodes formed by engagement of preformed corrugated strips with an exposed workpiece edge of a honeycomb core being constructed.
Another object is to provide efficient, economical welding apparatus for making metal honeycomb from corrugated metal strips utilizing one, two or more improved welding elements, each of which when used with strips formed for the purpose produces substantially simultaneously multiple spot welds across nodes formed by interengagement of corrugated metal strips and honeycomb formed therefrom.
Another object is to provide welding apparatus for making high quality metal honeycomb from preformed corrugated metal strips using two interchangeable rows of finger electrodes cooperable with an array of welding elements. A related object is to provide a simplified, reliable control system for mutually positioning the finger electrodes and the welding elements relative to each other and to the core panel under fabrication.
An additional object is to provide welding apparatus for making metal honeycomb from preformed corrugated strips having positioning means on a series of welding heads for positioning the preformed corrugated strips relative to an electrical welding element on each head, and having registry and advancing means to emplace the corrugated strip against the end of the core panel under fabrication whereby a honeycomb structure core panel is formed.